A lot of the groups of students I've blogged about working with here have been quite small - groups of 10 or less. One person I've met and discussed things with is faced with quite a lot of introductory lectures, to groups of several hundred students. What use is SL for something like that?
Obviously you can't use SL directly to deliver a lecture to this number of students, nor have them synchronously in the same sim even, not unless LL suddenly massively upgrade. But, is SL useless to you?
One of the obvious things SL offers most of us is the ability to make fairly good 3D models and film machinima. Are they as good as a professional would do in Maya/3DSMax etc? No, of course not. But, most of us can't afford the cash for these bits of software and although people complain about the learning curve for SL, the learning curve for Maya etc. is way steeper and longer, so we can't afford the time either. You're not using SL directly in class, you're using it as a tool to provide a better learning resource. It's not
immersive in the slightest, but that doesn't stop SL being a useful tool for a lecture to a large group in this way.
Another fairly obvious thing - do you expect all your students to only learn in class/contact time? I certainly don't, they read, research, etc. to learn as well, hopefully guided and facilitated by me. This is, in my limited experience of big group teaching, MORE important as the group size increases. If you've got a good stand-alone build (i.e. one that is engaging and works well when you're not there - and this is probably pretty immersive too) you can tell the students how to find it. You can enter SL for free after all, you're making it an optional additional resource (this might help you find the keener students faster too).
The particular person in this case is teaching a science subject - and so almost certainly gets practical time too. Depending on the institution and the course, they may well have groups of students doing different practical work at the same time. Say there are 10 groups, a group of 30 (based on the title) working in SL, further divided in SL into smaller groups could work well. It's probably quite staff intensive compared to the rest of the practical session, but it's certainly doable.
Another one your institution may like, or not, would be distance learning in the lecture theatre. You announce the time and place, SL and RL, and stream your audio, possibly even a webcam for video into SL. I believe you can even voice chat in "group messaging" so you could broadcast to your learners wherever they are in the grid this way just by using SL's voice tools. This lets your students pull their laptop into bed with them and still attend your lecture. Whilst I oppose the widespread use of voice in SL, being hard of hearing, in this case I wouldn't have an issue with it, or not a significant one. You are offering it as an option. I'd still be there, reading your lips in class, and I'm more likely to get a place that makes it easy to see your lips, so it's actually good for me too.
You may, of course, decide that you don't want to use any of these approaches. I still think SL is far from an ideal environment for delivering to such big classes, but as a tool for 3D modeling and presentation, excellent, and with a bit of imagination it's also there, always, as an extra resource for your students, even in these non-ideal situations.
